The advent of AdS/CFT has led to a quiet revolution of applying string theory beyond its traditional realm of quantum gravity and grand unification. In particular, recent developments have led to a breakthrough in our understanding of many strongly interacting systems that have been very challenging to study using standard perturbative methods. In this talk, I will give examples of what string theory can tell us about QCD and physics of the quark-gluon plasma as well as about condensed matter systems including models of high-temperature superconductivity.